1. Field of the Invention
The present invention relates to new powdered organosilicon anti-foaming compositions which are made by mixing organosilicon anti-foaming agents with solid organopolysiloxane carriers. The compositions can be used for treating aqueous solutions containing detergents.
The invention also relates to a process for maintaining the anti-foam activity of organosilicon anti-foaming agents which are stored in contact with washing powders by introducing the anti-foaming agents into the washing powders in combination with the disclosed organopolysiloxane carriers.
2. Description of the Prior Art
Published German Application No. 1,519,964 teaches preparing powdered anti-foaming compositions, which may be used in detergent solution, by mixing silicone oils with adsorbent materials such as urea, zeolites and silica gels, preferably in a solvent medium. While such compositions have an effective anti-foaming activity, they rapidly lose this activity when they are brought into prolonged contact with powdered detergents. Therefore, the anti-foaming agents cannot be packaged together with detergents and yet still remain effective.
Published French Application No. 2,194,771 teaches a method of safeguarding the anti-foaming activity of the usual organosilicon anti-foaming agents which are mixed with washing powders and then stored. The anti-foaming agents are coated with synthetic or organic matrices whch are solid at ambient temperature and which are water-soluble or dispersible. The coating technique consists of mixing the melted matrices with the anti-foaming agents and then spraying the mixture into a fluidized bed of a water-soluble solid material. This technique is unnecessarily complicated. Moreover, since the anti-foaming agents may exist in various physical states (liquids, pastes or solids) it is not always possible to readily obtain homogeneous and dry coatings.
French Pat. No. 2,084,632 discloses an anti-foaming composition made of four different materials, i.e., (1) an organic liquid which is insoluble in water, (2) a hydroxylated dimethylpolysiloxane oil or an organopolysiloxane resin which is soluble in benzene, (3) a silica or methylsilsesquioxane gel filler, and (4) an amino compound, an alkali metal hydroxide or an alkaline earth metal hydroxide.
Belgian Pat. No. 826,633 teaches a combination of three organosilicons which are combined with mineral oils. The preferred organosilicon mixture is made of (1) 55-96% by weight of a siloxane having the formula EQU CH.sub.3 Si(OCH.sub.3).sub.x O.sub.(3-x)/2
in which "x" has a value such that the methoxy radical is present in a weight percentage of 10%-35% by weight, (2) 2%-25% by weight of a copolymer made of (CH.sub.3).sub.3 SiO.sub.0.5 and SiO.sub.2 which is soluble in benzene and in which the ratio of (CH.sub.3).sub.3 SiO.sub.0.5 to SiO.sub.2 is between 0.5:1 and 1.2:1, and (3) 2%-25% of a methylpolysiloxane fluid having hydroxyl end groups which are attached to silicon.
Thus, there remains a need in the art for a simple yet effective means of protecting and maintaining the anti-foaming properties of organosilicons which will subsequently be added to detergents.